RELAÇÃO ENTRE USO E COBERTURA DA TERRA, GRUPOS HIDROLÓGICOS DOS SOLOS E RETENÇÃO POTENCIAL (S) EM MANANCIAL DE ABASTECIMENTO PÚBLICO NO CERRADO

Abstract

Understanding hydrological dynamics in watersheds used for public water supply requires an integrated analysis of land use and land cover and soil physical characteristics. This study analyzed the spatial relationship among land use and land cover, hydrologic soil groups, and potential retention, represented by the S parameter of the NRCS-CN method, in the Ribeirão Vereda watershed, located in the municipalities of Aragoiânia and Guapó, Goiás, Brazil, covering 35.71 km². Land use and land cover were mapped from a Sentinel-2/MSI image acquired on October 3, 2024, using bands 3, 4, and 8 at a spatial resolution of 10 m, supervised classification, and field verification at 28 points. The soil map was developed by integrating existing soil surveys, soil-relief relationships, and field verification. Soil classes were assigned to hydrologic soil groups A, B, C, and D and associated with the respective Curve Number (CN) values under antecedent moisture condition II. The CN values were used to estimate the S parameter, expressed in millimeters and adopted in this study as an indicator of potential precipitation retention according to the NRCS-CN method, without representing a direct measure of infiltration rate, effective soil water storage, or groundwater recharge. Agricultural land, pasture, and exposed soil accounted for 73.93% of the watershed area, whereas remaining vegetation formations represented 24.04%. The highest estimated S values occurred predominantly in agricultural areas located on higher and gently sloping surfaces, mainly associated with hydrologic soil group A. In intermediate sectors, the occurrence of groups B and C, associated with petroplinthite and increasing slope, was related to lower estimated S values. In the southern portion of the watershed, the lowest values occurred mainly in areas associated with hydrologic soil group D, with a predominance of Litholic Neosols and sparser vegetation cover. The results show that the influence of land use and land cover on potential hydrological conditions is not spatially homogeneous across the watershed, but is conditioned by its interaction with soil and relief characteristics.